1. Field of Invention
The present invention relates to the field of surfboards, and more particularly to an improved surfboard with a variable rocker.
2. Description of Related Art
A surfboard's rocker—its longitudinal upwards curvature, measured from its bottom surface—effects that surfboard's balance between speed and maneuverability more than any other design aspect. Less curved (flatter) rocker increases straight-line speed but decreases maneuverability. More curved rocker increases maneuverability but decreases straight-line speed.
This speed and maneuverability trade-off exists because typical surfboards are rigid which means their rockers are fixed shapes. Variable rocker eliminates this trade-off
The most common surfboard construction starts with rigid polyurethane (PU) or expanded polystyrene (EPS) foam slabs or “blanks”, typically reinforced with one or more stringers for further rigidity. After the foam is sculpted into the desired surfboard design, it is entirely encapsulated in a rigid skin by laminating fiberglass cloth to the foam, typically with polyester or epoxy resin. Because the fiberglass skin serves as a structural component, typical surfboard construction is a monocoque design, which excels at rigidity. Furthermore, typical surfboards are shaped to have features that increase their monocoque rigidity compared to a monocoque without that feature. For example, typical surfboards feature longitudinally convex (domed) deck shapes because laminating the fiberglass to that contour increases the longitudinal rigidity of the fiberglass itself and therefore the board as well.
Because typical surfboard construction emphasizes rigidity, the speed and maneuverability trade-off caused by fixed rockers is considered normal.
The next most common type of surfboard, colloquially called a “soft top”, “foamie” or “foam board”, is designed with soft exteriors in the interests of user and bystander safety, lower cost, and impact durability. Because their soft exteriors are not structural, soft tops are commonly reinforced for rigidity either internally with stringers or externally such as with a fiberglass layer bonded to their bottom surface, yet still are less rigid than conventional fiberglass monocoque surfboards. Despite a degree of flexibility, soft tops do not deliver variable rocker. Quite the opposite, the flexibility of soft tops typically decreases both speed and maneuverability
Soft tops are generally “floppy” meaning they have flexibility without predefined flex patterns, and they lack an ideal rate of “snap back” to their original shape when relieved from flex inducing forces. As such, soft tops tend to push water forward, rather than under the board, making them slow. And their floppy nature means soft tops tend to be less responsive to surfer input and thus are more difficult to maneuver.
Soft top surfboards demonstrate that flexibility alone does not create variable rocker.
The invention delivers variable rocker by giving surfboards a range of flexibility when flex-inducing forces are applied, sufficient snap back to their original shape when flex-inducing forces are relieved, and a flex pattern. When the invention flexes, it doesn't flop or bend in arbitrary ways. The various rocker shapes formed through its range of flexibility are deliberately designed to balance speed and maneuverability for that degree of flex.